Process for preparing 3-substituted methyl-7-acylamido-7-methoxy-2-cephem-4-carboxylic acid and its esters

ABSTRACT

Process for preparing an ester of 3-substituted methyl-7acylamido-7-methoxy(or hydrogen)-2-cephem-4-carboxylic acid and its corresponding sulfoxide by treating an ester of 3carbamoyloxymethyl(or 3-lower alkanoyloxymethyl)-7-acylamido-7methoxy(or hydrogen)-2-cephem-4-carboxylic acid with a hydrohalic acid or another compound containing an active hydrogen and then with an oxidizing agent. The products obtained are useful as intermediates in the preparation of antibiotics.

United States Patent n91 n11 3,859,282 Cheng et al. 1 Jan. 7, 1975 PROCESS FOR PREPARING OTHER PUBLICATI'ONS S-SUBSTITUTED METHYL-7-ACYLAMlDO-7-METHOXY-2- CEPHEM-4-CARBOXYLIC ACID AND ITS ESTERS Inventors: Theresa Y. Cheng, Newark; Sandor Karady, Elizabeth; Seemon H. Pines, Murray Hill; Meyer Sletzinger, North Plainfield; all of NJ.

Assignee: Merck & Co., Inc., Rahway, NJ

Filed:' July 14, 1971 Appl. No.: 162,703

us. Cl. 260/243 c, 424/246 Int. Cl C07d 99/24 Field of Search 260/243 C References Cited UNITED STATES PATENTS 12/1970 Long et al 260/243 C Nakarajan ct al., JACS, Vol. 93: 9, May 5. l97l. pp.

Primary Examiner-Nicholas S. Riz zo Attorney, Agent, or FirmWalter Patton; Julian S. Levitt; J; Jerome Behan 57 ABSTRACT 6 Claims, No Drawings .PROCESS FOR PREPARING 3-SUBSTITUTED METIIYL-7-ACYLAMIDO-7-METHOXY-2- CEPHEM-4-CARBOXYLIC ACID AND ITS ESTERS This invention relates to a novel process for preparing an ester of 3-substituted methyl-7-acylamido-7 methoxy(or hydrogen)-2-cephem-4-carboxylic acid (I, in fra). This invention also relates to the preparation of novel 3-substituted methyl-7-acylamido-7-methoxy-2- cephem-4-carboxylic acids and esters and the corresponding sulfoxides.

The products are useful as intermediates in the preparation of known cephalosporin compounds and also the recently discovered cephalosporins having a methoxy substituent in the 7-position in place of the hydrogen substituent of the known cephalosporins. The cephalosporin products which may be prepared from these novel intermediates are useful as antibiotics against gram-positive and gram-negative microorganisms.

Cephalosporins having a 7-methoxy substituent are effective against gram-negative bacteria including Escherichia cali, Proteus vulgaris, proteus mirabilis, Proteus morganii, Salmonella schottmuelleri, Klebsiella pneumoniae AD, Klebsiella pneumoniae B, and Paracolobactrum arizoniae and gram positive bacteria including Staphylococcus aureus, Streptococcus pyogenes and Diplococcus pneumoniae.

The cephalosporins are useful in removing susceptible micoorganisms from pharmaceutical, medical and dental equipment and as bactericides in industrial applications, for example, in water based paints and in the white water of paper mills to inhibit the growth of harmful bacteria.

This invention comprises treating an ester of 3- carbamoyloxymethyl(or 3-lower alkanoyloxymethyl)- 7-acylamido-7-methoxy(or hydrogen)-2-cephem-4- carboxylic acid (H, infra) with a hydrohalic acid, for example, hydrobromic acid, hydrochloric acid, hydroiodic acid and the like. Alternatively, in lieu of the hydrohalic acid there may be employed another compound having an active hydrogen. This reaction with the compound having an active hydrogen is conducted in the presence of a catalyst, for example, a non nucleophilic acid or a Lewis acid. Compounds having an active hydrogen are well known in the art and the following examples are merely illustrative of the type of compound which may be employed; inorganic acids such as hydrazoic acid and the like, organic acids, for example, lower alkanoic acid such as propionic acid, butyric acid and the like, arylcarboxylic acids such as benzoic acid and the like, haloacetic acids such as trifluoroacetic acid and the like, monoor polyhydroxybenzenes such as phenol, 2,4-dihydroxyphenol and the like or B-dicarbonylmethyl compounds, for example, ethyl acetoacetate, phenyl acetoacetate and the like.

To increase the reactivity of these active hydrogencontaining compounds a catalyst is employed in the reaction; for example, non-nucleophilic acids such as perchloric acid, benzenesulfonic acid and the like or a Lewis acid such as boron trifluoride, boron trichloride, aluminum chloride and the like.

The reaction with either the hydrohalic acid or other compound containing an active hydrogen may be conducted in any solvent in which the reactants are soluble and inert or substantially inert such as methylene chloride, tetrahydrofuran, chloroform, carbon tetrachloride, benzene, hexane, diethyl ether and the like. The

reaction may be conducted at a temperaturre in the range of from about C. to about C. In general, the reaction is conducted at a temperature in the range of from about OC.-to about 5C. The reaction time naturally varies with the temperature at which the reaction is conducted and may vary from about 5 minutes up to about 25 hours; however, at a temperature in the range of 0C. to about 5C., the reaction is usually complete within 15 hours. The following equation illustrates this process:

wherein R is acyl; R is hydrogen or methoxy; R is a blocking group; R is amino or methyl, and X is halo such as bromo, chloro, iodo and the like, azido, lower alkanoyloxy such as propionyloxy, butyryloxy and the like, aroyloxy such as benzoyloxy and the like, a monoor polyhydroxyphenyl such as 4-hydroxyphenyl', 2,4- dihydroxyphenyl and the like or a B-dicarbonylmethyl compound of the formula:

R400 Ci 3n COR wherein R and R are the same or different radicals selected from methyl, ethyl, n-propyl, n-butyl and the like.

The acyl radical, R, may be any one of the acyl functions presently known in the cephalosporin art. For example, R may be an acyl radical of the formula:

w ll

wherein R is benzyl, p-hydroxybenzyl, a-aminobenzyl, or-carboxybenzyl, a-azidobenzyl, allylthiomethyl, butylmercaptomethyl, D-(or L)-4-amino-4-carboxybutyl, a-chloro-n-heptyl, ethyl, 3- or S-nitrobenzyl, phenethyl, B,B-diphenethyl, thiophene, thiophenoxy, 2- thienylmethyl, a-amino-Z-thienylmethyl, a-methylaminobenzyl, a-( N-methylsulfamyl)benzyl, D(-)-aguanidino-2-thienylmethyl, D(-)-a-guanidinobenzyl, 4-guanidino-phenoxymethyl, 4- guanidinomethylbenzyl, cyanomethyl, 2,6-dimethoxy- 4-guanidinophenyl, 2- 0r 3-furylmethyl, l-H-tetrazoll-yl-methyl and the like.

In carrying out the reactions described herein, it is preferred to protect the 4-carboxy group and also other groups in the nucleus which need protection, for example, other carboxy groups, amino groups or hydroxy groups. Maximum yields are obtained by-employing these protected compounds. Naturally, the groups which are preferred are those which are easily removed. Examples of these protecting groups, R in the formulas, are trichloroethyl, tert-butyl, benzoylmethyl, p-methoxybenzyl, benzyl, benzhydryl and the like. Amino groups can be protected by trichloroethoxycarbonyl, tert-butoxycarbonyl, p-chlorobenzoyloxycarbonyl and the like.

' noic acid such as propionic acid, butyric acid and the like or an alkali metal salt of an aryl carboxylic acid, for example, an alkali metal salt of benzoic acid and the like. The reaction may be conducted at a temperature in the range of from about 20 to about 100C. In general, the reaction is conducted at a temperature in the range of from about to 25C. Any solvent which is inert or substantially inert to the reactants may be employed, for example, dimethylformamide, p-dioxane, dimethylsulfoxide, acetonitrile, tetrahydrofuran and the like. The following equation illustrates this reaction:

tom

(l VIII wherein R, R, R and halo are as defined above and X is lower alkoxy, for example, methoxy, ethoxy, npropoxy and the like, cyano, hydroxy, lower alkanoyloxy such as propionyloxy, butyryloxy and the like or aroyloxy, for example, benzoyloxy and the like and M is hydrogen or an alkali metal such as sodium and the like.

The ester of the 3-substituted methyl-7-aeylamido-7- methoxy(or hydrogen)-2-cephem-4-carboxylic acids (V) may be converted to its corresponding sulfoxide (IV, infra) by treatment with an oxidizing agent, for example, a peracid such as m-chloroperbenzoic acid, periodic acid, perphthalic acid, peracetic acid, perbenzoic acid, pertrifluoroacetic acid, performic acid and the like or with a salt of a peracid, for example, an alkali metal salt of periodic acid such as sodium periodate and the like or with hydrogen peroxide. The oxidation is conducted in an inert solvent such as methylene chloride, carbon tetrachloride, chloroform, benzene, the

lower alkanols such as methanol, ethanol and the like,- acetone or water at a temperature in the range of from about C. to about 50C. and preferably at about 0C. The following equation illustrates this process:

i l O= N CHrX wherein R, R and Y are as defined above and X is halo, cyano, lower alkoxy, protected hydroxy, lower alkanoyloxy, aroyloxy, monoor polyhydroxyphenyl or a B-dicarbonylmethyl.

The product (IV) of the oxidation step may also contain some of the A cephem compound. When an alcohol is employed as the solvent in the oxidation reaction or when the oxidizing agent employed is an acid, the product obtained is generallya mixture of the A and A cephems. This mixture is completely converted to the A cephem compound by the isomerization procedure described below.

The ester of the 3-substituted methyl-7-acylamido-7- methoxy(or hydrogen)-2-cephem-4-carb0xy-l-oxide (IV, supra) can then be converted to the corresponding A -cephem compound (VI, infra) by treating the A sulfoxide with an isomerizing agent, for example, an alcohol or an organic base or an adsorbent such as alumina, silica gel and Florisil and the like and then treating the A sulfoxide (VI) with a reducing agent such as stannous chloride and the like to obtain the ester of the 3-subs'tituted methyl-7-acylamido-7-methoxy (or hydrogen)-3-cephem-4-carboxylic acid (VII, infra). The following equation illustrates process:

0 0 l l RNH- fggj RNH- 1 ll l O= N oam o= N cmx:

OR2 on o 0 IV VI Reducing Agent s RNHWI/ 0== N -omx VII wherein R, R, R and X are as defined above.

The 3-carbamoyloxymethyl(or 3-lower alkanoyloxymethyl)-7-acylamido-7-methoxy(or hydrogen)-2- cephem-4 carboxylic acid (II, supra) described above are prepared by the isomerization of the corresponding A -cephem compound (VIII, infra) (a mixture of the A and A cephems) by treating the A -cephem compound (or the mixture) with an isomerizing agent. This may be accomplished by dissolving the A -cephem compound (VIII) in an appropriate solvent such as methanol, benzene, ethyl acetate, chloroform, diethylether, methylene chloride or mixtures of these solvents and treating these solutions with Florisil, silica gel, alumina and the like or by treating the A -cephem compound (VIII) with a base, for example, an organic base such as pyridine or a trialkylamine such as triethylamine and the like or inorganic base, for example, an alkali or alkaline earth metalhydroxide, alkoxide and the like such as sodium hydroxide, potassium hydroxide, aluminum hydroxide, sodium methoxide, sodium ethoxide and the like. The following equation illustrates this reaction employing the A -cephem compound; however, employing a mixture of the A and A -cepham compound will afford similar results:

wherein R, R, R and Y are as defined above.

Those compounds (Vlll) wherein the acyl radical, 7B-(D-5-amino-5-carboxyvaleryl), is replaced by other acyl radicals are prepared by treating compound Villa with an acylating agent in a suitable solvent such as chloroform, dioxane, methylene chloride, acetonitrile and the like in the presence of a silyl compound, for example, a trialkylated silane trifluoroacetamide such as N-trimethylsilyl trifluoroacetamide and the like at a temperature in the range of from about room temperature up to about 50C. The 7B-(D-5-amino-5- carboxyvaleryl) group is then removed by removal of the protecting group (R which results in the cleavage of the 7B-(D-S-amino-S-carboxyvaleryl) group. The following equation illustrates this process:

VIII

wherein R, R, R and R are as defined above.

The compound containing the 7-methoxy substituent and the 7-D-5-amino-5-carboxyvaleramido substituent (Vllla) was originally isolated as a single colony from soil on an agar slant and is obtained by fermentation process. A sample of this microorganism is on permanent deposit with a culture collection of the Northern Utilization Research and Development Branch of the U.S. Department of Agriculture at Peoria, Illinois, and has been assigned the cultural number NRRL-3802. The 7B-(D-5-amino-5-carboxyvaleramido)-3- (carbamoyloxymethyl)-7-methoxy-3cephem-4- carboxylic acid is produced during the aerobic fermentation of suitable aqueous nutrient mediums under controlled conditions via inoculation with the organism Streptymyces lactamdurans. In general, any medium which is a source of carbon and nitrogen may be employed. The exact amount of the carbohydrate and nitrogen sources will depend on the other ingredients comprising the fermentation medium but, in general, the amount of carbohydrate is usually about 1% to 6% by weight of the medium and the amount of available nitrogen, either alone or in combination, is usually in the amount of from about 0.2% to about 6% by weight of the medium. The medium described below is illustra:

tive of a medium which is suitable for the preparation; however, it should be understood that other media may be employed.

Medium:

1% Blackstrap Molasses 1% National Brewer's Yeast 2.5% Difco agar pH 7.0 Water to volume The fermentation is carried out at a temperature in the range of from about 20C. to about 37C. but for optimum results it is preferable to conduct the fermentation at a temperature in the range of from about 24C. to 32C. The pH of the nutrient medium suitable for growing the Streptomyces lactamdurans culture and for producing 7/3-(D-5-amino-5-carboxyvaleramido)-3- (carbamoyloxymethyl)-7-methoxy-3-cephem-4- carboxylic acid should be in the range of from about 6.0 to about 8.0.

The 7B-(D-5amino 5-carboxyvaleramido)-3- carbamoyloxymethyl-7-methoxy-3-cephem4- carboxylic acid is recovered from the fermentation broth by passing the filtered broth at pH 7.0 over a strongly basic anion exchange resin eluting the product from the resin with 3% ammonium chloride. in 90% methanol, repeating the adsorption at pH 7.2 to 8.0, eluting with 5% aqueous sodium chloride, adsorbing the active eluates at pH 2.0 on a strongly acidic cation exchanger of the sulfonate type, eluting the product with a 2% aqueous pyridine solution and recovering the pyridinium salt which salt can be converted to other salts or to the free acid in accordance with procedures well known in this art.

The blocking and protecting groups, R, employed above, can be removed at any time in the process to afford those compounds wherein R? would be hydrogen. For example, the ester group is removed to afford the a catalyst such as palladium on carbon or with a strong organic or inorganic acid such as hydrochloric acid, sulfuric acid, boron trifluoride etherate, formic acid, trifluoroacetic acid, trichloroacetic acid, nitrobenzoic acid and the like.

The following examples illustrate the novel process of this invention. However, the examples are illustrative only and it will be apparent-to those skilled in the art that other reagents similar to those described in the following examples may be employed to afford similar results.

EXAMPLE 1 Benzhydryl ester of 7-methoxy-3-methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxy-l -oxide Step A: Benzhydryl ester of 3-carbamoyloxymethyl- 7-methoxy-7-(2-thienylacetamido)-2-cephem-4- carboxylic Acid The benzhydryl ester of 3-carbamoyloxymethyl-7- methoxy-7-(2-thienylacetamido)-3-cephem-4- carboxylic acid (1.0 g.) is applied on a column of Florisil (20.0 g.) packed with benzene. A solution of 10% ethyl acetate in benzene is allowed to drip through the column overnight. The A -isomer thus formed is eluted with 40% ethyl acetate in benzene. After evaporation the product is found to be pure and has the following physical characteristics.

NMR: (Solvent CDCl 8=6.32 (2'H, d, J =2Hz), 5.10 (4-H, d,J =2Hz), 5.32 (6-H), 3.40 (7-OCH ,s), 4.52 (10H ,s), 3.82 (13-11 s).

Step B: Benzhydryl ester of 3-bromomethyl-7- methoxy-7-(2-thienylacetamido)'2-cephem-4- carboxylic Acid In a system void of atmospheric moisture, a saturated solution of hydrogen bromide (0.0132 mole) in methylene chloride (110.0 ml.) is added dropwise to a stirred, cold (in ice) solution of benzhydryl ester of 3- carbamoyloxymethyl-7-methoxy-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid (0.0056 mole) in methylene chloride (40.0 ml.). After the addition is over, the reaction mixture is condensed to 30 ml. and is used directly in the next step.

Step vC: Benzhydryl ester methoxymethyl-7-(2-thienylacetamido)-2-cephem-4- carboxylic Acid The methylene chloride solution of the benzhydryl ester of 3-bromomethyl-7-methoxy-7-(2- thienylacetamido)-2-cephem-4carboxylic acid from Step G, and calcium carbonate (29.5 g.) isstirred at C. while methanol (50.0 ml.) is added dropwise. The mixture is stirred for another 1% hours and is worked up by partition between methylene chloride and a aqueous sodium bicarbonate solution. The organic layer is washed with water, dried over sodium sulfate and evaporated to give 3 g. of crude product. This is purified by column chromatography to yield 2.3 g. of pure benzhydryl ester of 7-methoxy-b 3- of 7-methoxy-3 8 methoxymethyl-7-(2-thienylacetamido)-2-cephem-4- carboxylic acid.

NMR: (Solvent CDCl 8=6.2 (2-H, d, J=2Hz), 5.1 (4-H, d, J=2Hz), 5.38 (6H, s), 3.39 (7OCH s) 3.8 5 (IO-H s), 3.1 (OCH s), 3.82 (--H ,J =10Hz).

Step D: Benzhydryl ester of 7-methoxy-3- methoxymethyl-7-(Z-thienylaceta'mido)-2-cephem-4- carboxy-l-oxide To a stirred, cooled (in ice) solution of benzhydryl ester of 7-methoxy-3-methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid (2.3 g.) in 50 ml. of a 1:1 mixture of methylene chloride and isopropanol is added dropwise a solution of mchloroperbenzoic acid (1.0 g.) in methylene chloride 15 ml.). After stirring an hour in ice and an additional 36 hour at room temperature, the reaction mixture is washed successively with a sodium bicarbonate solution, water and saturated sodium chloride solution. The organic solution is evaporated to give l.0 g. of benzhydryl' ester of 7-methoxy-3-methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxy-l-oxide which also contains the A cephem isomer.

EXAMPLE 2 Dibenzhydryl ester. of 7,8-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-cyanomethyl-7-methoxy-2 cephem-4-carboxyl oxide Step A: Dibenzhydryl ester trichloroethoxy-carbonylamino-S- carboxyvaleramido) -3-carbamoyloxymethyl- 7-methoxy-2-cephem-4-carboxylic Acid The dibenzhydryl ester of 7B-( D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-3-cephem-4- carboxylic acid (10 g.) is slowly eluted through a Florisil column (200 g.) with a 10% solution of ethyl acetate in benzene. The A compound thus formed is then removed from the column with a 40% solution of ethyl acetate in benzene. Removal of the solvent yields the substantially pure dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-2-cephem-4- carboxylic acid (6.5 g.). This material shows a single spot on thin layer chromatography.

UV: )tmax. (CH OH) 247.5 e7200 NMR: (Solvent CDCl )'8=3.4l (7-CH O, s), 4.72 (IO-H, s), 5.34 (6-H, s), 6.3 (2-H, d,J. =-1.5 Hz), 5.16 l-H, d, JAB: 1.5Hz).

Step B: Dibenzhydryl ester trichloroethoxy-carbonylamino-S- carboxyvaleramido)-3-(bromomethyl)-7-methoxy-2- cephem-4-carboxylic Acid To a cold solution (in ice) of the dibenzhydryl ester of 7 B-(D-5-trichloroethoxycarbonylamino-5- carboxyvaleramido)-3-carbamoyloxymethyl-7- methoxy-Z-cephem-4-carboxylic acid (15.0 g.) in methylene chloride (150 ml.) is added dropwise hydro- 60 gen bromide in methylene chloride (60 ml., 0.57 N).

The mixture is stirred at 05C. for 1 hour. The reaction is stopped by bubbling off the excess hydrogen bromide with nitrogen. The white precipitate of ammonium bromide is removed by filtration. The reaction mixture is extracted twice with cold water, dried and evaporated to yield 21.6 g. of the crude dibenzhydryl ester of 7 B-(D-S-trichloroethoxyearbonylamino-S- carboxyvaleramido)-(3-bromomethyl)-7-methoxy-2- of m- D-scephem-4-carboxylic acid. It is about 80% pure as indicated by the NMR spectrum.

NMR: (Solvent CDCl 8=3.42 (7-CH O, s) 4.07 (IO-H q), 5.35 (6-H, s), 6.3 (2-H, d, .l =2l-lz), 5.35 (4-H, d, JAB=2HZ).

Step C: Dibenzhydryl ester of 7,8-(D-5- trichloroethoxy-carbonylamino-5-carboxyvaleramido)-(3-cyanomethyl)-7-methoxy-2-cephem-4- carboxylic Acid H The dibenzhydryl ester of 7fi-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-bromomethyl)-7-methoxy-2-cephem-4-carboxylic acid (5.0 g.) is dissolved in dimethylsulfoxide (100 ml.). The solution is cooled to l-15C. To this is slowly added cuprous cyanide (0.6 g.). The reaction mixture is allowed to warm up to room temperature and is stirred for another 6 hours. The reaction mixture is then partitioned between methylene chloride and water. The methylene chloride layer is dried over anhydrous sodium sulfate, filtered and the solvent removed by evaporation. Purification by column chromatography using silica gel H with chloroform as the eluant yields the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino--carboxyvaleramido)- (3-cyanomethyl)-7-methoxy-2-cephem-4-carboxylic acid. Thin layer chromatography shows a single spot. UV: )tmax. (CH OH) 2480 66900 NMR: (Solvent CDCl 6=3.42 (7CH O, s), 3.17 (1041;, s), 5.33 (6-H, s), 6.27 (2-H, d, J =2Hz), 5.05 (4-H, d, J -2H2).

Step D: Dibenzhydryl ester trichloroethoxy-carbonylamino-S- carboxyvaleramido)-3(cyanomethyl)-7-methoxy-2- cephem-4-carboxyl -oxide An ice cold solution of dibenzhydryl ester of 7B-(D- 5-trichloroethoxycarbonylamino-S- carboxyvaleramido)-3-(cyanomethyl)-7-methoxy-2- cephem-4-carboxylic acid (3.04 mmoles) in methylene chloride ml.) is added dropwise a solution of mchloroperbenzoic acid (0.6 g., 3.0 mmoles) in methylene chloride (20 ml.). After one hour the reaction mixture is washed with an aqueous sodium bicarbonate solution and then with water. The reaction mixture is dried over sodium sulfate, filtered and the solvent is removed to afford dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-(cyanomethyl)-7-methoxy-2-cephem-4-carboxy-loxide.

of vpn-svEXAMPLE 3 Benzyl ester of 3-methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxy-l-oxide Step A: Benzyl ester of 3-acetoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic Acid The benzyl ester of 3-acetoxymethyl-7-(2- thienylacetamido)-3-cephem-4-carboxylic acid (100 mg.) is applied on a Florisil (2 g.) column packed with benzene. A solution of 10% ethylacetate in benzene is allowed to drop through the column overnight. The A isomer thus formed is eluted with a mixture of ethylacetate and benzene (3: 10). Evaporation of the solvent affords 82 mg. of pure benzyl ester of 3-acetoxymethy1-7- (2-thienylacetamido)-2cephem-4carboxylic acid. Thin layer chromatography shows a single spot. NMR: (Solvent CDCl 8 558 (7-H, q), 5.2 (6-H, d), 6.37 (2-H, d, J =1Hz), 5.01 (4H, d, J =lHz), 4.58 (IO-H s), 3.80 (13-H s), 1.97

10 Lola...)

Step B: Benzyl ester of 3-bromomethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic Acid A cooled solution (in ice) of benzyl ester of 3- acetoxy-methyl-7-(2-thienylacetamido)-2-cephem-4- carboxylic acid (77 mg., 0.01 mmole) is stirred while hydrogen bromide (0.5 ml.) in methylene chloride (0.32 mmole) is added dropwise. The reaction is stopped 50 minutes later by simply bubbling off the excess hydrogen bromide with nitrogen. Removal of the solvent affords the benzyl ester of 3-bromomethyl-7- (2-thienylacetamido)-2-cephem-4-carboxylic acid which is employed directly in Step C.

Step C: Benzyl ester of 3-methoxymethyl-7-(2 thienylacetamido)-2-cephem-4-carboxylic Acid The benzyl ester of 3-bromomethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid is dissolved in methanol. After standing at room temperature for 20 minutes the reaction mixture is poured into a dilute sodium bicarbonate solution and extracted with methylene chloride. The organic layer is washed with aqueous sodium chloride and dried. Removal of the solvent affords 35 mg. of crude product. The pure benzyl ester of 3-methoxymethyl-7-( 2- thienylacetamido)-2-cephem-4-carboxylic acid is then isolated by preparative thin layer chromatography (15% ethyl acetate in chloroform as eluant). NMR: (S0lvent CDCl 8=5.61 (7-H,q), 5.21 (6-H, d), 6.25 (2-1-1, d, J =lHz), 5.02 (4H, d, J,,,,=1Hz). 5.17 (lO-H partially visible), 3.82 (13-H s), 3.18 (OCH s).

Step D: Benzyl ester of 3methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxy-1-oxide By substituting for the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-(cyanomethyl)-7-methoxy-2-cephem-4-carboxylic acid of Example 2, Step D, the benzyl ester of 3- methoxymethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid and following substantially the procedure described therein, there is obtained the benzyl ester of 3- methoxymethyl-7-(2-thienylacetamido)-2-cephem-4- carboxy-l-oxide.

EXAMPLE 4 mmole) in methylene chloride (20 ml.) and tetrahydrofuran (11 ml.) is stirred for 5 hours at 0C. The reaction mixture is washed with a sodium bicarbonate solution and then with water. The reaction mixture is dried over. sodium sulfate, filtered and the solvent removed to afford the crude product. The crude product is purified by elution through a column containing silica gel employing a solution of chloroform and ethyl acetate (8:2) as the eluant to afford dibenzhydryl ester of 7B-(D-5-trichloroethoxycarbonylamino-S-carboxyvaleramido)-3-(4-hydroxybenzyl)-7-methoxy-2-cephem-4-carboxylic acid. This product shows a single spot on thin layer chromatoghy- NMR: (Solvent CDCl 8=5.78 (2-H, d, J =lHz), 4.8 (4-H, d, J =lHz), 5.4 (6-H, s), 3.37 (7-OCH s), 3.3 (lO-H partially visible), 6.85 [phenol (4Hs), q, J =H2].

Step B: Dibenzhydryl ester of 7B-(D-5-trichloroethoxycarbonylamino-S-carboxyvaleramido)3-(4- hydroxybenzyl)-7-methoxy-2-cephem-4-carboxy-1- oxide An ice cold solution of dibenzhydryl ester of 7B-(D- 5-trichloroethoxycarbonylamino-5- carboxyvaleramido)-3-(4- hydroxybenzyl)-7-methoxy-2cephem-4-carboxylic acid (3.0 g., 3.04 mmoles) in methylene chloride (20 ml.) is added dropwise a solution of m-chloroperbenzoic acid (0.6 g., 3.0 mmoles) in methylene chloride (20 ml.). After one hour the reaction mixture is washed with an aqueous sodium bicarbonate solution and then with water. The reaction mixture is dried over sodium sulfate, filtered and the solvent is removed to afford the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-(4-hydroxybenzyl)-7-methoxy-2-cephem-4-carboxyl-oxide along with some of the A cephem compound.

EXAMPLE 5 Dibenzhydryl ester of 7B-(D-5- t'richloroethoxycarbonylamino-S-carboxyvaleramido)- 3-(2-ethoxycarbonyl-3-oxobutyl)-7-methoxy-2- cephem-4-carboxyl -oxide Step A: Dibenzhydryl ester of 7,8-(D-5-trichloroethoxycarbonylamino-Scarboxyvaler amido)-3-(2- ethoxycarbonyl-3-oxobutyl)-7methoxy-2-cepehm-4- carboxylic Acid U To a solution of the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylami-S-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-2-cephem-4 carboxylic acid (0.425 g.) in methylene chloride (5.0 ml.) is added a solution of ethylacetoacetate (0.07 ml.) and boron trifluoride etherate (0.08 ml.) in methylene chloride (1 ml.). The reaction mixture is stirred for two hours and then diluted with ethyl acetate Q00 rnl). Th SOlLltlQ1ll is washed with an aqueous sodium bicarbonate solution and then dried over anhydrous sodium sulfate. The solution is filtered and the solvent removed to afford crude product which is purified by chromatographing on a column containing silica gel G using chloroform as the eluant to afford dibenzhydryl ester of 7B-(D-5-trichloroethoxycarbonylami-6carboxyvaleramido)-3(Z-ethoxy carbonyl- 3 oxobutyD-7-methoxy-2-cephem-4- carboxylic acid. This product shows a single spot on thin layer chromatorgraphy.

Step B: Dibenzhydryl ester of 7B-(D-5-trichloroethosycarbonylamino-S-carboxyvaleramido),3- (Z-ethoxycarbonyl-3-oxobutyl)-7-methoxy-2-cephem- 4-carboxy- 1 -oxide By substituting for the dibenzhydryl ester of 7/3-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-(cyanomethyl)-7-methoxy-2-cephem-4-carboxylic acid of Example 2, Step D, an equimolar'quantity of the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-(2-ethoxycarbonyl-3oxobutyl)-7-methoxy-2- cephem-4-carboxycarboxylic acid and by following substantially the procedure described therein, there is obtained the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-(2-ethoxycarbonyl-3-oxobutyl)-7-methoxy-2- cephem-4-carhoxy-l-oxide.

EXAMPLE 6 by chromatographing through a column of silica gel G to yield the substantially pure benzhydryl ester of 3-v azidomethyl-7-methoxy-7-(2-thienylacetamido)-2- cephem-4-carboxylic acid.

Elemental analysis for C H N O S Calc: C, 58.4; H, 4.35; N, 12.32;

Found: C, 58.4; H, 4.72; N, 12.36.

EXAMPLE 7 Benzyl ester of 7-(D-5-trichloroethoxycarbonylamino- 5-carboxyv.aleramido)-(3-hydroxymethyl)-7-methoxy- 2-cephem-4-carboxylic Acid A solution of the benzyl ester of 7-(D-5- trichloroethoxy-carbonylamino-S- carboxyvaleramido)-3-bromomethyl)-7-methoxy-2- cephem-4-carboxylic acid (0.7 g.) in 5 ml. of pH 7.5 buffer and 13.5 ml. of p-dioxane is allowed to stand at room temperature for 2 and 7% hours. The reaction mixture is extracted successively with ethyl acetate and the organiclay'er is washed with an aqueous saturated sodium chloride solution. After drying, the solvent is removed by evaporation and the product is purified by column chromatography [silica gel column with 2% methanol in a mixture of hexane andchloroform (1:1) as the eluant] to afford benzyl ester of 7-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- (3-hydroxymethyl)-7-methoxy-2-cephem-4-carboxylic acid.

of mo-sester of 7B-(D- trichloroethoxycarbonylamino --carboxyvaleramido)- 3-bromomethyl-7-methoxy-2-cephem-4-carboxylic acid (1 mmole) in dimethylformamide ml.) is added sodium benzoate (1 mmole). The reaction mixture is stirred at room temperature overnight. The reaction mixture is diluted with water and the product is extracted with methylene chloride. The methylene chloride solution is washed with an aqueous sodium bicarbonate solution and then with water. The solution is dried over magnesium sulfate, filtered and the solvent removed to afford dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-S-carboxyvaleramido)- 3-benzoyloxymethyl-7-methoxy-2-cephem-4- carboxylic acid. Step B: Dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-benzoyloxymethyl-7-methoxy-2-cephem-4-carboxyl-oxide By substituting for the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-(cyanomethyl)-7-methoxy-2-cephem-4-carboxylic acid of Example 2, Step D, the dibenzhydryl ester of 7- B-(D-5-trichloroethoxy-carbonylamino-5- carboxyvaleramido)-3-benzoyloxymethyl-7-methoxy- 2-cephem-4-carboxylic acid and following the procedure described therein, there is obtained dibenzhydryl ester of 7B-(D-5-trichloroethoxycarbonylamino-5- carboxyvaleramido)-3-benzoyloxymethyl-7 methoxy- 2-cephem-4-carboxy-l-oxide. Preparation of Starting Materials 7-Methoxy-3-methoxymethyl-7-(2-thienylacetamido)- 3-cephem-4-carboxylic Acid Step A: Monosodium Salt of 7B-(D-5-amino-5- carboxyvaleramido)-3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic Acid Modified Fermentation Process:

Step 1: Slants A lyophi'lized tube of Streptomyces lactamdurans culture (MA-2908) was opened asceptically and the organism transferred to a medium of the following composition:

Medium X1:

1% Blackstrap Molasses 1% National Brewers Yeast 2.5% Difco agar pH 7.0

Water to volume The slants are inoculated for seven days at 28C. When stored in the cold, the slants are stable for more than 13 weeks.

Step 2: Seed Stages: Two Stage System First Seed: The first seed is inoculated directly from the slant of Step 1 to 40 ml. of 1% of Primary Dried Yeast N.F., pH 7.0 (obtained from the Yeast Product Corporation) in a 250 ml. baffled Erlenmeyer flask. The flasks were then shaken on a 220 rpm. rotary shaker with a 2 inch throw at 28C. for a period of from two to three days.

Second Seed: A 2.5% inoculum from the first seed stage was added to a flask containing a 2% Fleischmann 5-150 yeast autolysate, pH 7.0. The growth in this stage is characteristically light and the incubation, performed as in the first stage, was not extended beyond 48 hours.

Step 3: Production Medium The production medium contains per liter of distilled water: 30 g. distillers solubles; 7.5 g. of Primary Dried Yeast NE. and 0.25% v/v Mobilpar-S defoamer. The

medium is adjusted to pH 7.0 with a small amountof concentrated sodium hydroxide solution, dispensed into Erlenmeyer flasks and autoclaved for 15 or 20 minutes at 121C. After cooling the-medium received a 2.5% inoculum of the seed obtained in Step 2. The time of incubation can vary from about 50 hours to 100 hours but an incubation period of about 72 hours is preferred. The volume of media in each flask can vary from 30 to 50 ml. but 40 ml. was used routinely. The level of inoculum can vary from 1% to 5%; but, in practice, a 2.5% level is generally employed.

Step 4: Assay When the fermentation was complete, the cells were removed by centrifugation and the broth was diluted with phosphate buffer, pH 7.0. The concentration of 7,8-(D-5-amino-5-carboxyvaleramido)-3- (carbamoyloxymethyl)-7-methoxy-3-cephem-4- carboxylic acid in the fermentation broth was determined by the standard biological-disc assay method. The assay organism employed was Vibrio percolans (ATCC 8461 Filter paper discs are emersed into the diluted broths and placed on the surface of agarcontaining Petri dishes that had been inoculated with the assay organism Vibrio percolans (ATCC 8461). Also placed on these Petri dishes are discs that had been dipped previously in standard solutions containing known concentrations of 7,8-(D-5-amino-5' carboxyvaleramido)-3-carbamoyloxymethyl)-7- methoxy-3-cephem-4-carboxylic acid. The discs were incubated overnight at 28C. and the diameters of the zones of inhibition recorded. The concentration of product and the fermented broth is calculated by interpolation from the standard curve which relates zone diameter with the known concentrations of standard solutions of the product. By this procedure it was calculated that Streptomyces lactamdurans MB-2908 produced 78.6 ig/ml. of 7B-(D-5-amino-5- carboxyvaleramido)-3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic acid in the modified fermentation process.

Step 5: Isolation The filtered broth is adjusted to pH 7.0 with dilute hydrochloric acid and 2,900 ml. is passed through a column containing a strongly basic anion exchange resin (100 g.) having a styrene-divinylbenzene matrix (Dowex l X 2 chlorid cycle resin) at 10 ml./minute. The spent solvent is collected in 500 ml. fractions. The resin column is washed with water and eluted with 3% ammonium chloride in methanol. The eluate is collected in ml. fractions. The spent fractions are combined, the pH adjusted to pH 7.2 to 8.0 with dilute sodium hydroxide and adsorbed on a strongly basic .anion exchange resin (100 g.) having a styrenedivinylbenzene matrix (Dowex 1 X 2 chloride cycle resin) at 14 ml./minute. The column is washed with water and eluted with 5% aqueous sodium chloride. The eluate is collected in 50 ml. fractions and concentrated. The concentrate is diluted to 500 ml., adjusted from pH 8.8 to pH 2.0 with dilute hydrochloric acid and adsorbed on 25. ml. of a strongly acidic cation exchange resin of the sulfonate type having a styrenedivinylbenzene matrix (Dowex 50 X 2 hydrogen cycle resin) at 2.5 ml./minute. The column is washed with 25 ml. of water then eluted with 2% pyridine until the pH of the column effluent rose to pH 7 (54 ml.). The eluate thus obtained is adjusted to pH 8.0 with dilute sodium hydroxide and concentrated under vacuum to remove the pyridine and afford the monosodium salt of 7B-(D-5-amino-S-carboxyvaleramido)-3- carbamoyloxymethyl-7-methoxy-3-cephem-4- carboxylic acid.

Elemental analysis for C H N SO Na:

Calc.: C, 41.0%; H, 4.5%; N, 12.0%; S, 6.8%;

Found: C, 39.31%; H, 4.76%; N, 11.16%; S, 6.46%.

Step B: carboxyvaleramido)-3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic Acid The monosodium salt of 7-(D-5-amino-5- carboxyvaleramido)-3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic acid (20.5 gm.) is dissolved in a mixture of acetone (80 ml.) and aqueous 10% dipotassium hydrogen phosphate (240 ml.). To this solution is added dropwise trichloroethoxycarbonyl chloride gm., 118 mmoles) in acetone (80-ml.). During the addition the pH of the solution is kept at 9.1 by gradual addition of 2.5 N sodium hydroxide solution. After minutes the mixture is extracted with ethyl acetate, the ethyl acetate layer discarded, and the aqueous layer is acidified to pH 2.5 with concentrated hydrochloric acid. The precipitated product is extracted into ethyl acetate. After drying over sodium sulfate and removing the solvent under vacuum the title compound is obtained as an oil. This crude product is used without purification in the next step.

Step C: Di-benzhydryl ester of 7-(D-5- trichloroethoxycarbonylamino-4-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-3-cephem-4- carboxylic Acid To a solution of 7-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- '3-carbamoyloxymethyl-7-methoxy-3-cephem-4- carboxylic acid in ethyl acetate (500 ml.) is added diphenyldiazomethane (17 gm.) in ether (200 ml.). After agitating the mixture overnight, it is extracted successively with sodium bicarbonate and sodium chloride solutions. The solvent is evaporated from the dried solution to afford a crude product which is purified by chromatography on silica gel. A 2:1 mixture of chloroform and ethyl acetate is used for elution. This material showed a single spot of thin layer chromatography. UV: )tmax. 2650 67000 (CH OH) Step D: Dibenzhydryl ester of trichloroethoxy-carbonylamino-S-carboxyvaleryl)-(2- thienylacetyl)-amino]-3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic Acid A mixture of dibenzhydryl ester of 7-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-3-cephem-4- carboxylic acid (6.0 g., 6.3 mmoles), N-trimethylsilyl trifluoroacetamide (4.7 gm., mmoles), 2-

thienylacetyl chloride (3.42 ml., 25 mmoles), and chloreform ml.) is warmed at 47C. for 16 hours. After the solvent is removed by evaporation, the crude reaction mixture is extracted'with hexane and further purified by chromatography on 1 kg. of silica gel using 10% ethylacetate in chloroform as the eluant. The purified product exhibits a satisfactory NMR spectrum.

UV: )tmax. 265 E5810 (CH OH) and shows a single spot on thin layer chromatography 7-(D-5-trichloroethoxycarbonylamino-S- Step E: Benzhydryl ester of 3-carbamoyloxymethyl- 7-methoxy-7-(2-thienylacetamido)-3-cephem-4- carboxylic Acid The dibenzhydryl ester of 7-[(D-5- trichloroethoxycarbonylamino-S-carboxyvaleryl)-(2- thienylacetyl)-amino]'3-carbamoyloxymethyl-7- methoxy-3-cephem-4-carboxylic acid (4.2 gm., 3.8 mmoles) is dissolved in ethyl acetate (30 ml.) and added to a mixture of 90% aqueous acetic acid (30 ml.) and zinc dust (12 gm.). The mixture is stirred vigorously for 5 7% hours at room temperature. After the zinc is filtered off, the excess acetic acid is removed by washing the ethylacetate solution with water. The title compoundis isolated in the same manner as described above in Step D. It is characterized by thin layer chromatography (7% CH OH in 1:1 Cl-lcl zn-hexane) as a single spot material.

IR: (CHCl 1740, 1800 cm; UV: )tmax. 263 65800 v V The term Florisil used in the application is the tradename for an activated magnesium silicate.

By following substantially the procedures described in Examples '1 and 4, all of the products disclosed herein may be prepared by the novel process of this invention. Thus, by substituting the appropriate hydrohalic acid' for the hydrogen bromide of Example 1, Step B, or by substituting for phenol of Example 4, Step A, an appropriate compound containing an active hydro- 30 gen and following the respective procedures described in Example 1, Steps A-D and Example 4, Steps A and' B, all-of the products described in Table I may be prepared.

TABLE 1 Example number R R1 R1 R X n OCH3 -CC13 -NH 01 -CII(HJ l lHz 10.. OCH; NH 011 o1n 1m 0 Q ll cn c OH 11 -oo113 OCH; -NH 0 t (l I(IJC(CII:):UH3

cmc -0H.-

12 OC1h cr )2 NH2 13 a. OCII3 CH(): NH 6) ll it -cn c 14 O -ocn3 0H 2 NH (d 4 l l CCF3 LSFCH 0 15 0 oc1n -cH )g NHQ I .mh 'l 16 -oo1r3 -o1r 2 c1n Br The examples are illustrative ofthe novel method disclosed; however, it is to be understood that the invention is not limited by the specific examples but embraces all the variations and modifications falling within the scope of the foregoing discussion and appended claims.

What is claimed is:

l. A process for preparing a compound of the formula:

dihydroxyphenyl, B-dicarbonylmethyl of the formula:

wherein R and R are the same or different alkyl radicals selected from the group consisting of methyl, ethyl, n-propyl and n-butyl; R is an easily removable blocking group not reacting with HX selected from the group consisting of trichloroethyl, tert-butyl, benzoylmethyl, p-methoxybenzyl, benzyl and benzhydryl; which comprises bringing in contact in an inert organic solvent selected from the group consisting of methylene chloride,- tetrahydrofuran, chloroform, carbon tetrachloride,

benzene, hexane and diethyl ether at a temperature range of about C. to C. for 5 minutes to 25 hours a compound of the formula:

0 A l cmol m (JOR' wherein R, R and R are as defined above and R is amino or methyl with a compound containing an active hydrogen of the formula: HX, wherein X is as defined above wherein when X is other than chloro, bromo or iodo the reaction is carried out in the presence of a non-nucleophilic acid or a Lewis acid selected from the group consisting of perchloric acid, benzenesulfonic acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boron trifluoride, boron trichloride and aluminum chloride.

2. The process according to claim 1 for preparing the benzhydryl ester of 3-bromomethyl-7-methoxy-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about 70C. to about 100C. the benzhydryl ester of 3- carbamoyloxymethyl-7-methoxy-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid with hydrogen bromide.

3. The process according to claim 1 for preparing the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-(bromomethyl)-7-methoxy-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about 70C. to 100C. the dibenzhydryl ester of 7B-(D-5-trichloroethoxycarbonylamino-S- carboxyvaleramido)-3-(carbamoyloxymethyl)-7- methoxy-Z-cephem-4-carboxylic acid with hydrogen bromide.

4. The process according to claim 1 for preparing the benzyl ester of 3- bromomethyl-7-(2- thienylacetamido)-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about C. to C. the benzyl ester of 3- acetoxymethyl-7-(Z-thienylacetamido) 2-cephem-4- carboxylic acid with hydrogen bromide.

5. The process according to claim 1 for preparing the dibenzhydryl ester of 7B-(D-5- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-(4-hydroxybenzyl)-7-methoxy-2-cephem-4- carboxylic acid which comprises bringing in contact at a temperature range of about 70C. to 100C. the dibenzhydryl ester of 'lB-(D-S- trichloroethoxycarbonylamino-5-carboxyvaleramido)- 3-carbamoyloxymethyl-7-methoxy-2-cephem-4- carboxylic acid with phenol inthe presence of perchloric acid.

6. The process according to claim 1 for preparing the dibenzhydryl ester of 7B-(D-5- 

1. A PROCESS FOR PREPARING A COMPOUND OF THE FORMULA:
 2. The process according to claim 1 for preparing the benzhydryl ester of 3-bromomethyl-7-methoxy-7-(2-thienylacetamido)-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about 70*C. to about 100*C. the benzhydryl ester of 3-carbamoyloxymethyl-7-methoxy-7-(2-thienylacetamido)-2-cephem-4-carboxylic acid with hydrogen bromide.
 3. The process according to claim 1 for preparing the dibenzhydryl ester of 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3-(bromomethyl)-7 -methoxy-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about -70*C. to 100*C. the dibenzhydryl ester of 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3 -(carbamoyloxymethyl)-7-methoxy-2-cephem-4-carboxylic acid with hydrogen bromide.
 4. The process according to claim 1 for preparing the benzyl ester of 3-bromomethyl-7-(2-thienylacetamido)-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about -70*C. to 100*C. the benzyl ester of 3-acetoxymethyl-7-(2-thienylacetamido)-2-cephem-4-carboxylic acid with hydrogen bromide.
 5. The process according to claim 1 for preparing the dibenzhydryl ester of 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3-(4-hydroxybenzyl) -7-methoxy-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about -70*C. to 100*C. the dibenzhydryl ester of 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3-carbamoyloxymethyl-7-methoxy-2-cephem-4-carboxylic acid with phenol in the presence of perchloric acid.
 6. The process according to claim 1 for preparing the dibenzhydryl ester of 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3-(2-ethoxycarbonyl -3-oxobutyl)-7-methoxy-2-cephem-4-carboxylic acid which comprises bringing in contact at a temperature range of about -70*C. to 100*C. 7 Beta -(D-5-trichloroethoxycarbonylamino-5-carboxyvaleramido)-3-carbamoyloxymethyl-7-methoxy-2-cephem-4-carboxylic acid with ethyl acetoacetate in the presence of boron trichloride. 